In photoshop I can easily merge layers when I get too many. But I can't find this function in Illustrator. I'm using a dot grid for colouring and I have to duplicate the image/object to grow the grid. But now I have tons of layers that are slowing down my computer and preventing it from saving the AI file. I've tried grouping the objects but it just puts the multitude of layers in a sublayer which doesn't help.

Does Illustrator have a merge layer option that will take a bunch of objects and merge them into one object?

The Layers Panel in Illustrator is actually a "Layers and Objects" panel. It not only shows layers, but can show all objects as well. If you see things labeled <path> then it's an object, not a layer.

Chances are you are seeing the objects. When you Group objects it collects them in to a <Group>, which is like a sublayer but still seen as an object which is why it has the < and > brackets.

A great many objects will indeed slow down illustrator. There's no real way to get around the slowdowns when you hit them. The best you can do is turn off visibility of objects that aren't needed at the moment. The more things that must be drawn, the slower the app gets. It's been this way for years with complicated files.

Until Illustrator is made 64-bit and possibly multi-threaded more, there's not much that can be done.

Thank you for your help. Unfortunately that wasn't able to solve my problem.

To be clear this is what I'm doing. I'm creating a Roy Litchenstien style piece of art that uses a grid of dots to provide colour instead of a solid colour (replicatong old fashioned comic art).

To grow the dot grid I must duplicate the original grid a number of times. However, Illustrator is recognizing each individual dot as a <path>, an object. Therefore I have tens of thousands of these objects which is slowing my computer down and making it impossible to save. At this point I've barely completed one quarter of the dots I need to use for colouring.

Is there a way I can group these multiple dot <path>s into one <path>? Failing that, is there anything else anyone can suggest to make this process of dot colouring more efficient and less cumbersome for both me and my computer? I'm at my wits end.

A great many objects will indeed slow down illustrator. There's no real way to get around the slowdowns when you hit them. The best you can do is turn off visibility of objects that aren't needed at the moment. The more things that must be drawn, the slower the app gets. It's been this way for years with complicated files.

Quoted for emphasis.

Monika's suggestion of using pattern fill is a very good one. A shape with a pattern fill is seen as a single object.

Well actually yes and no, it all depends on what is slowing you down and what the OP needs, so it might be something they are not aware of and could help them navigate and make using the layer panel speed up and keeping it uncluttered, easy and quick to scroll through on the other hand it may not be what the OP is looking for in which case they will continue to seek other ways to make what they want work.